A novel uniformly doped barrier modulated ultra-deep-submicron poly-Si thin film transistor with very low subthreshold slope

Abstract

In this paper, the characteristics of a novel device structure, uniformly doped ultra-deepsubmicron poly-Si barrier modulated thin film transistor (BM-TFT), are investigated and compared with conventional poly-Si TFT. Use of uniform doping provides a solution from problems associated with random dopant fluctuations. The suppression of the leakage current of the TFT by introducing barrier modulation is verified and presented. The device is optimized with respect to channel length, doping of channel, spacer dielectric and gate dielectric material. Simulations resulted in I OFF of ~2 × 10 −11 A μm −1 , I ON of ~2mA μm −1 , I ON /I OFF of 10 8 , subthreshold slope of 144 mV/dec and DIBL of 119 mV V −1 for PolyGate/HfO 2 /Poly-Si coplanar BM-TFT at temperature. of 300 K, gate length of 60 nm, oxide thickness of 5 nm, film thickness of 10 nm, low-k spacer thickness of 20 nm and V DD of 2.5 V.